In general, a micro electro mechanical systems (MEMS) magnetic field sensor based on a capacitive sensing technology includes a drive electrode, which is movable n reaction to a magnetic field, and a fixed electrode which senses the variation of capacitance corresponding to the drive electrode.
A capacitive MEMS magnetic field sensor is disclosed in U.S. Pat. No. 6,664,786.
Regarding the principle of the magnetic field sensor, if a reference current is applied to a drive electrode in a predetermined direction, the drive electrode moves in a positive or negative direction from a fixed electrode by Lorenz force produced depending on the direction and the intensity of a magnetic field introduced into the magnetic field sensor from an outside.
In this case, the distance between the two electrodes or the overlapped area therebetween is varied to vary the capacitance. The variation of the capacitance or a signal varied corresponding thereto are detected so that the magnetic field can be sensed.
However, since Lorenz force used to sense the magnetic field is significantly weaker than gravity, satisfactory mechanical displacement may not be obtained due to the limitation in the design of a sensor structure such as a spring.
In addition, when an AC current or a DC current is applied to the drive electrode for the driving of the drive electrode to detect a varied signal, a desirable signal may be not detected due to the mixture of currents.